I've been doing sting lifts 5x5 for nearly six months now and have had some good results in increased strength but I'll be stopping at the end of may and having a month or so to cut. Afterwards I'm planning on focussing on increasing mass. Does any of you guys know of an effective routine/split to recommend? Preferably based mainly on compounds

No not at all but after this month it will be six months of 5x5 so I want to take the strength gains I've made and use them to put on more mass than I have. I'm gonna have 4-6 weeks of cutting then change the routine up because I'm starting to not enjoy stronglifts now.

Well according to ACSM, 8-12 rep range is best for maximum hypertrophy. But in my opinion if you are getting good increases in strength on 5x5, then there is a strong chance you may find yourself just spinning your wheels for a while looking for some other routine that probably isn't going to give you much better results. The best way to add mass is to get stronger. I can appreciate that you say you are getting bored, but I haven't seen very many lifters that have been at it for only 6 months that have great form on squats unless they've been under some great instruction. There are a lot of micro aspects to lifting form that I think most people would find interest in if they were more strategic about studying those lifts (squats, deadlifts, bench press, standing presses, pendelay rows). Also you may find more interest in the 5x5 routine by just adding in some accessory movements like shrugs, calf raises, barbell curls, skull crushers, pull ups and dips through out the week.Sorry if that's not more helpful, but I just think it might be a mistake to abandon a routine that you are still getting results on.

klaatu, I am about where you are on Stronglifts 5x5, 6 months in and while my progress has slowed I am still seeing strength gains. Maybe I am wanting to see more physical changes in my body, but I am not going to argue about continuing to gain strength. I continue to look at some of the other programs that are talked about on SL 5x5, such as Madcow, the 5/3/1 and others. As Justin mentioned, I am hopeful that the more strength I gain the heavier the weights I will be able to lift, which should help with muscle definition.

I've noticed small changes on my whole body, I'm just going to lower the weights for a bit, up the reps and try and pack on the lean mass for a few months to see what I can do. An experiment I suppose, then I'll start 5/3/1 and see how that goes:)